Temperature swing adsorption methods are known in the art for use in adsorptive separation of multi-component fluid mixtures, and gas mixtures in particular. Many conventional temperature swing adsorption processes are used for preferentially adsorbing one component of a feed gas mixture on an adsorbent material to separate it from the remaining feed gas components, and then subsequently to regenerate the adsorbent material to desorb the adsorbed component and allow for cyclic reuse of the adsorbent material. However, conventional temperature swing adsorption methods are typically limited in their efficiency due in part to limitations in heat and/or mass transport phenomena in the desorption or regeneration of the adsorbent material used in an adsorptive separation system, and also to limitations in the adsorption phase of the temperature swing adsorption process.
One shortcoming of typical conventional temperature adsorption processes is the inefficient adsorption of a feed gas component on the adsorbent material, which may result from the rapid increase in temperature of the adsorption front when moving through the adsorbent material due to the heat of adsorption released as the gas component is adsorbed. In many conventional temperature swing adsorption methods, such increases in the temperature of the adsorbent material during adsorption may result in decreased adsorbent capacity associated with “hot spots” in the adsorbent material and a corresponding decrease in efficiency of the temperature swing adsorption process. Another shortcoming of typically conventional temperatures swing adsorption methods is the inefficient desorption or regeneration of the adsorbent material, which may result from the difficulty in uniformly heating the adsorbent material as thermal energy is required to meet the heat of desorption of the adsorbed compound during desorption or regeneration. Such non-uniformities in the heating of the adsorbent material may typically result in retained adsorption of a gas component associated with “cold spots” in the adsorbent material, or may require the application of an unnecessarily large thermal flux to sufficiently desorb the gas component, which may lead to undesirably high heating costs and leave the adsorbent material unnecessarily overheated following desorption.
Further, conventional temperature swing adsorption methods typically employ adsorbent contactor structures such as adsorbent beds for contacting gas components with the adsorbent material. Exemplary known adsorbent contactors include packed bead or parallel plate adsorbent structures for adsorptive gas separation processes such as thermal and/or pressure swing adsorption processes, for example. However, some shortcomings of certain of the adsorbent contactors of the prior art relate to poor hydrodynamic, mass transport, and thermal characteristics of the contactor structure. In such cases, the poor thermal characteristics may undesirably result in either high thermal mass, which may require an undesirably large thermal energy flux to effect a given temperature change in the structure, and/or lower than desired thermal conductivity, which may result in undesirably large temperature differences within the structure, for example. Such undesirable thermal characteristics of certain adsorbent contactors of the prior art may contribute to some of the shortcomings of conventional temperature swing adsorption methods as described above. Aside from heat transport limitations, the poor hydrodynamics of certain conventional temperature swing adsorption structures may undesirably limit fluid throughput due to fluidization limitations, as in the case of beaded adsorbent beds. Further, in certain conventional systems, undesirably low mass transfer rates may limit the permissible cycle speed and also lower the dynamic selectivity of the cyclic adsorption-desorption process by limiting the adsorption selectivity of the system to only the adsorbent's inherent equilibrium selectivity, which may be undesirably low for separation of a given fluid mixture.